一种手持浸入式新型激光浊度计设计.pdf

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传感器与微系统( T'ransducer and Microsystem Technologies)
2012年第31卷第7期
种手持浸入式新型激光浊度计设计“
刘升…2,郜洪文3,黄超群',储焰南
(1.中国科学院安徽光学精密机械研究所环境光谱学研究室,安徽合肥230031;
2.淮北师范大学计算机科学与技术学院,安徽淮北235000;
3.同济大学环境科学与工程学院污染控制与资源化研究国家重点实验室,上海200092)
摘要:浊度是水质的一项重要指标。为了快速、准确地测量浊度,设计了一种手持浸入式便携浊度计
浊度计基于透射光法,发光源使用带光电二极管(PD)的850nm小功率激光管,激光管在发射电路地控制
下产生1kHz的调制光東,内置PD用于保持发光强度的恒定。光接收电路使用 PD BPW82接收透过试样
的光束,采用直流恢复电路消除低频背景光干扰,通过精密整流电路和滤波电路从调制信号中取出表示浊
度的电压信号。软件上利用微处理器的运算能力简化了电路设计,省去了对数放大器。给出了标定算法
和浮点数存储方法。
关键词:浊度测量;激光;透射光法;直流恢复电路
中图分类号:TP274;TH741
文献标识码:A文章编号:10009787(2012)07-0114-03
Design of a new type of hand-hold immersion
laser turbidimeter
IIU Sheng", GA0 Hong-wen, HUANG Chao-qun, CHU Yannan
1. Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China;
2. College of Computer Science and Technology, Huaibei Normal University, Huaibei 235000, China
3. College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
Abstract: Turbidity is an important index of water quality. In order to rapidly and accurately measure turbidity of
water, a new type of hand-hold immersion laser turbidimeter is designed. The method of measuring turbidit
based on transmitted light mode. The 850nm low power laser-diode with photo diode(PD) is used as light source
The laser-diode generates modulated beams at 1 KHZ controlled by transmitting circuit. The light intensity is kep
constant by the PD BPW82 photodiode receives the light beam transmitting from the samples. The DC restoration
circuit is used to eliminate inteference of low-frequency background light. Turbidity signal is obtained through
precise rectification circuit and filtering ircuit from the modulating signal. The design of cireuit is simplified and
logarithmic amplifier is left out due to the operation ability of microprocessor. Calibration algorithm and storing
methods of floating point number is given
Key words: turbidity measurement; laser; transmitting light mode; DC restoration cireuit
引言
但对于浸人式浊度测量,多次实验后发现采用散射光浊度
液体浊度测量在供水、酿酒、制药、环境保护及卫生防法,光源发出的光线经液体散射后容易受到外界液体的影
疫等诸多行业和部门有着广泛的用途。国内外用于浊度测响,这样就增加了结构设计的复杂性和成本。而采用透
量的便携式浊度计都不能直接浸入试样中直接测量,而是射光法测量浊度,应用内置PD的激光发射管为发射光源,
通过样品瓶取试样放入仪器中测量。直接浸入式浊度测量对发射光进行调制,设计性能优良的发射电路和接收电路,
的主要问题是消除环境光的干扰,保证仪器的稳定性和重这样设计的仪器结构简单、成本低、稳定性好,其测量范围
现性。常见的浊度测量方法有透射光浊度法、散射光浊度为0-100NTU,分辨率0.1NVTU,基本误差为士3%。
法和积分球浊度法(散射+透射法)。尽管散射光法和积1仪器结构和工作原理
分球法的灵敏度较高,而且适合于较大范围的浊度测定,
激光浊度仪结构如图1所示,水等液体可以自由进入
收稿日期:2012-02-20
*基金项目:国家“十一五”科技支撑计划资助项目(2008BAJO8B13